The invention relates to a press for pressing casings, cable shoes or similar items onto cables or other metallic conductors or bodies. Such presses are especially used in connection with high-voltage installation work. They have a concavely shaped upper die into which the casing and the conductor contained therein are placed. At the upper die a cylinder is attached in which a plunger is movable, which plunger moves the lower die in the direction of the upper die, thereby deforming the casing and the conductor contained therein, if any, and in this manner creates the desired press bonding. In order to ensure operational safety of the press bonding, a specific degree of deformation must be adhered to, which cannot be left to the operator but must be achieved automatically by corresponding means in the press itself. Also, in order to enable the press to function economically and safely, it must be capable of deforming casings or workpieces having different diameters without prior conversion or installation adjustments.
In this connection, German AS 19 40 854 and German OS 22 44 105 disclose presses whose upper dies have wedge-shaped recesses into which the casings or workpieces to be pressed are inserted, and into which they penetrate with varying depth according to their diameters. In the area of the wedge-shaped recesses, there are sensing elements which determine the depth of penetration, and based thereon, ascertain the diameter of the workpiece or casing and terminate the feed of the lower die at a point when the required degree of deformation has been reached. These presses, however, are of complicated mechanical construction and do not permit a choice in the design of the upper die, which in turn results in the inability to manufacture certain desirable cross sectional configurations of the pressed workpiece.
Another press known to the state of the art and serving the same purpose, is disclosed in German patent 16 27 811 and shows an arrangement of two pistons in a cylinder having two chambers, i.e. a press piston and a dosing piston. Coaxially with these pistons, there is a steering mechanism. Under the effect of the pressure medium, introduced into the cylinder, the press plunger is initially moved in the direction of the upper die until the lower die attached thereto engages the workpiece to be pressed. The steering element includes a pressure medium volume which is located between the dosing piston and the press plunger, and as a consequence of the increase in pressure thus incurred, the press plunger is activated by the dosing piston for the purpose of subsequent pressing. The construction of such a press is extremely expensive, if for no other reason than the necessity of two pistons. If there is air in the pressure fluid, which cannot always be avoided when the press is used as a portable unit on construction sites, an incorrect grade of deformation and a faulty pressing will result, because of the air in the sealed pressure medium which determines the depth of penetration.